Optically active carboxylic acid esters are used in various fields as pharmaceuticals, intermediates of physiologically active substances, and intermediates in the synthesis of natural products.
Hitherto, a method by reacting a carboxylic acid with an alcohol using an asymmetric catalyst is a known method for producing optically active carboxylic acid esters. For example, a method is proposed in Patent Document 1 in which an optically active carboxylic acid ester is produced by reacting racemic carboxylic acids with an alcohol in the presence of benzoic anhydride or a derivative thereof by using tetramisole or benzo-tetramisole as a catalyst.
However, in the kinetic resolution as described in Patent Document 1, one enantiomer of the racemic carboxylic acids to be the raw material is selectively esterified, and thus the yield of the optically active carboxylic acid ester is theoretically a maximum of 50%.
Hence, a method for producing an optically active carboxylic acid ester using the dynamic kinetic resolution is proposed in Patent Document 2. According to the method described in Patent Document 2, it is possible to produce an optically active carboxylic acid ester at a high yield of over 50% by increasing the amount of carboxylic acid to be esterified through racemization of the optically active carboxylic acid that is the other enantiomer as well as by producing an optically active carboxylic acid ester through selective esterification of one enantiomer of the racemic carboxylic acids.
Patent Document 1: PCT International Publication No. WO2009/113428
Patent Document 2: PCT International Publication No. WO2012/169575